/**
 * @name: lianjuntao
 * @author: mac
 * @date: 2022-10-14 14:39
 * @description:
 * @update: 2022-10-14 14:39
 * @path: src/directive
 */

import Vue from "vue";

// v-dialogDrag: 弹窗拖拽属性
Vue.directive("dialogDrag", {
    bind(el, binding, vnode, oldVnode) {
        const dialogHeaderEl = el.querySelector(".el-dialog__header");
        const dragDom = el.querySelector(".el-dialog");
        //dialogHeaderEl.style.cursor = 'move';
        dialogHeaderEl.style.cssText += ";cursor:move;";
        dragDom.style.cssText += ";top:0px;";

        // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
        const sty = (function () {
            if (window.document.currentStyle) {
                return (dom, attr) => dom.currentStyle[attr];
            } else {
                return (dom, attr) => getComputedStyle(dom, false)[attr];
            }
        })();

        dialogHeaderEl.onmousedown = e => {
            // 鼠标按下，计算当前元素距离可视区的距离
            const disX = e.clientX - dialogHeaderEl.offsetLeft;
            const disY = e.clientY - dialogHeaderEl.offsetTop;

            const screenWidth = document.body.clientWidth; // body当前宽度
            const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取)

            const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
            const dragDomheight = dragDom.offsetHeight; // 对话框高度

            const minDragDomLeft = dragDom.offsetLeft;
            const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;

            const minDragDomTop = dragDom.offsetTop;
            const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;

            // 获取到的值带px 正则匹配替换
            let styL = sty(dragDom, "left");
            let styT = sty(dragDom, "top");

            // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
            if (styL.includes("%")) {
                styL = +document.body.clientWidth * (+styL.replace(/%/g, "") / 100);
                styT = +document.body.clientHeight * (+styT.replace(/%/g, "") / 100);
            } else {
                styL = +styL.replace(/px/g, "");
                styT = +styT.replace(/px/g, "");
            }

            document.onmousemove = function (e) {
                // 通过事件委托，计算移动的距离
                let left = e.clientX - disX;
                let top = e.clientY - disY;

                // 边界处理
                if (-left > minDragDomLeft) {
                    left = -minDragDomLeft;
                } else if (left > maxDragDomLeft) {
                    left = maxDragDomLeft;
                }

                if (-top > minDragDomTop) {
                    top = -minDragDomTop;
                } else if (top > maxDragDomTop) {
                    top = maxDragDomTop;
                }

                // 移动当前元素
                dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`;
            };

            document.onmouseup = function (e) {
                document.onmousemove = null;
                document.onmouseup = null;
            };
        };
    }
});
